A Long Term Evolution (LTE) system is evolution of a 3G mobile communication system. FIG. 1 is a schematic diagram of network architecture of an LTE system. As illustrated in FIG. 1, the LTE system consists of three parts, i.e., evolved Nodes B (eNBs) 11, an Evolved Packet Core (EPC) 12 and User Equipment (UE) 13. The EPC includes Mobility Management Entities (MMEs) and Serving Gateways (S-GWs); and a plurality of eNBs 11 at an Evolved Universal Terrestrial Radio Access Network (E-URTAN) side access to MMEs 121/S-GWs 122 through S1 interfaces, and all the eNBs 11 are connected through X2 interfaces.
With the constantly expansion of macro-network scale, the number of users is continuously increased and data bandwidth demands of the users are continuously increased. Because frequency of use of 3rd-Generation (3G) mobile communication networks and LTE networks is relatively high, and as compared with the Global Systems of Mobile Communication (GSM), their signal penetrating ability is relatively poor, indoor coverage becomes a difficulty in network optimization, and the indoor coverage of the 3G networks or LTE networks is generally implemented by means of setting up indoor distribution systems. However, under existing conditions, the indoor distribution systems generally can only be set up in some hotels, medium-grade and high-grade residential districts or public hotspot places. For common residential districts, due to the limitation of various conditions, the indoor distribution systems cannot be set up. Therefore, indoor 3G or LTE signals are very weak and even there is no signal at all, causing a very big influence on user experience.
For this reason, a femto cell system is put forward. The used common broadband or operator transmission access is implemented by accessing a core network of a security gateway and an operator through the Internet, such that wireless signal coverage is provided for the users. The femto cell system mainly consists of femto cells and femto cell gateways, the femto cells are divided into 3G standard HNBs and LTE standard HeNBs according to the different used wireless technologies.
FIG. 2 is a schematic diagram of network element architecture of an LTE standard femto cell system. As illustrated in FIG. 2, a home evolved node B gateway (HeNB GW) 21 is introduced into the LTE system and a plurality of HeNBs 22 are linked under the HeNB GW 21. Firstly, the HeNB GW 21 is connected to at least one HeNB 22 through an S1 link; and secondly, the HeNB GW 21 is further accessed to a core network device 23, which specifically may be an MME, through an S1 link. Besides, the HeNB 22 may also be directly accessed to the core network device 23 through an S1 link.
Each network element in the LTE system bears IP services through IP. The IP bearer may be Internet Protocol Version 4 (IPV4) and may also be Internet Protocol Version 6 (IPV6). Whether IPV4 or IPV6, neighboring network elements are required to use the same IP bearer. At present, an IP type is not carried in protocol S1 “INITIAL UE MESSAGE”, thus the MME can only determine a service bearer type which needs to be assigned to a user through an S1 signaling bearer type, i.e., the service bearer type is the same as the S1 signaling bearer type, which causes no problem when macro base stations or the HeNBs 22 are directly connected with the MME. When the HeNBs 22 are connected with the MME through the HeNB GW 21, as long as the HeNB GW 21 can support conversion between IPV4 and IPV6, no problem is caused either. However, when the HeNBs 22 are linked with the MME through the HeNB GW 21 and a user plane does not pass through the HeNB GW 21, i.e., the service bearer between the HeNBs 22 and the MME is directly connected, the MME cannot know the bearer type of the HeNBs 22 at this moment. If the MME assigns an IPV6 address and the HeNB only supports IPV4, the service bearer between the HeNBs 22 and the MME cannot be successfully set up.